Glass laminated products have contributed to society for almost a century. Beyond the well known, every day automotive safety glass used in windshields, glass laminates are used in most forms of the transportation industry. They are utilized as windows for trains, airplanes, ships, and nearly every other mode of transportation. Safety glass is characterized by high impact and penetration resistance and does not scatter glass shards and debris when shattered. Glass laminates find widespread use in architectural applications, as well.
Safety glass typically consists of a sandwich of two glass sheets or panels bonded together with an interlayer of a polymeric film or sheet which is placed between the two glass sheets. One or both of the glass sheets may be replaced with optically clear rigid polymeric sheets such as, for example, sheets of polycarbonate materials. Safety glass has further evolved to include multiple layers of glass and/or polymeric sheets bonded together with interlayers of polymeric films or sheets.
The interlayer is typically made with a relatively thick polymer sheet that exhibits toughness and adheres to the glass in the event of a crack or crash. Over the years, a wide variety of polymeric interlayers have been developed to produce laminated products. In general, it is desirable that these polymeric interlayers possess acceptable levels of: optical clarity (haze of less than 4%) when laminated to glass or other clear rigid material, impact resistance, penetration resistance, ultraviolet light resistance, long term thermal stability, adhesion to glass and/or other rigid polymeric sheets, ultraviolet light transmittance, moisture absorption, moisture resistance, long term weatherability, among other characteristics. Widely used interlayer materials include complex multi-component compositions comprising polymers such as polyvinylbutyral (PVB); polyurethane (PU), polyvinylchloride (PVC), metallocene-catalyzed linear low density polyethylenes, ethylenevinyl acetate (EVA), ethylene acid copolymer ionomers, polymeric fatty acid polyamides, polyester resins such as poly(ethylene terephthalate), silicone elastomers, epoxy resins and elastomeric polycarbonates. Acid copolymers have become more widespread in their use for fabricating transparent laminates. U.S. Pat. Nos. 3,344,014; 3,404,134; 4,663,228 and 4,668,574; 4,906,703; 5,476,553; 5,478,402; 5,344,513; 5,759,698; 5,763,062; 5,895,721; 6,238,801; 6,150,028; 6,432,522; U.S. Patent Application No. 2002/0155302; U.S. Patent Application No. 2003/0044579; WO 99/58334; WO 00/64670; and WO 2004/011755; and WO 2006/057771 each discloses the use of acid copolymers and/or ionomers as interlayers in laminated glazing.
In the production of conventional ionoplastic resins and products made therefrom, particularly those used in the manufacture of safety glazing, it can be necessary to maintain control of the environmental conditions used to manufacture and store said products. Specifically, humid conditions can have deleterious effects on the properties of interlayer materials used in the manufacture of safety glazing, and on the performance of said safety glazing. These problems can be exacerbated by the tendency of conventional ionoplastic resins used in safety glazing to absorb moisture from the air.
Processes to control the environment of the manufacturing and/or storage facilities used in producing said ionoplastic resins and the products made therefrom can be complex, and such processes can be inefficient or ineffective for controlling the effect of the storage environment on said products. This can result in products of inconsistent quality and/or performance. In some instances this can result in sub-standard product that is not suitable for further use.
In safety glazing applications, there is a need to improve the adhesion of ionoplastic materials to rigid structural layers, to minimize or reduce the effect of improper storage or the lack of effective environmental controls on the performance of ionoplastic materials used in the manufacture of laminate safety glazing and to provide ionoplastic materials wherein variances in moisture content do not substantially reduce adhesion in a laminate glazing article.